The bomb was buried in a dirt road in Lower Dir district and apparently detonated by remote control as the minibus passed by, said Ejaz Abid, the local police chief. There was little left of the vehicle after the explosion, just a mass of crumpled metal.

Two children were among the dead, said Mahmood Aslam, a local government official. The vehicle was not carrying any tribal elders, anti-Taliban militia commanders or others from the area frequently targeted by militants, he said.

"I don't understand why the passenger vehicle was targeted," he said.

Dilawar Khan, a survivor, said he heard a huge blast, and the passengers suddenly dove to the ground.

"I was listening to people's cries but unable to see anything as dust and smoke engulfed the air," said Khan. "Then I found myself in the hospital with my leg and hand bandaged," he said.

No group has claimed responsibility for the attack, but the Pakistani Taliban has carried out many similar bombings in the northwest.